The Ice Cream Overrun & 6 Other Active Ice Cream Ingredients

What constitutes an ice cream? To answer this question, let us first consider the raw materials needed to make a high-quality ice cream.

The most important components include:

• High quality dairy ingredients (with proper proportions of butterfat and MSNF)
• Sugar
• Stabilizers
• Flavoring agents
• Coloring agents
• Permitted food additives
• Optional ingredients (can include egg yolk, spices, herbs, nuts, fresh/dried fruits, etc.)

A standard ice cream consists of 10% butterfat, 11% MSNF, <14% sugar, <0.4% emulsifier and stabilizer, 64.6% water, and a maximum of 100% overrun (i.e. 50 litres of the ice cream should incorporate an equivalent of 50 litres of water).

1. Butterfat

This ingredient can be obtained from fresh cream, whipping cream, unsalted butter, butter oil (anhydrous milk fat), or concentrated sweetened cream (with 65% butterfat content).

It should be incorporated into the mix at the rate of 10% minimum but can go up to 15% by weight.

Butterfat contributes to rich creamy flavor and texture of the ice cream. The homogenization process uniformly distributes the butterfat globules in the ice cream.

This uniform distribution imparts a smooth feel to the mouth, provides EFA (e.g. oleic acid) and energy.

Ice cream with higher butterfat content tends to have smaller sized ice crystals. The correct amount of butterfat lessens the amount of incorporated air during whipping while less butterfat will lead to more incorporated air in the ice cream.

2. Milk Solid Non-Fat (MSNF)

Composed of minerals (such as calcium, magnesium, citrates) and proteins, which consists of caseins and whey proteins (β-lactoglobulins and α-lactalbunins). These should consist at least 11% of the total volume of the mix.

MSNF used in the mix can be obtained from skim milk powder, whey powder, condensed skim milk,

Nutritionally, MSNF provides proteins (amino acids) and calories from the sugar. They also contribute to the texture of the ice cream.

These solids stabilize the air cells. They also hold the water and prevent syneresis.

Again, these solids have emulsification effect. The minerals act in conjunction with the proteins (e.g. calcium citrate) to enhance stabilization.

3. Sugar

Various types of sugar can be used to formulate the mix. They may include cane sugar and sugar beet (in granulated form), high fructose corn syrup (HFCS), dextrose, honey, etc. the sugars enhance the flavor of the product and supplies calories to the ice cream.

These sugars impart the preservative effect in ice cream and depresses the freezing point of the ice cream mix.

Other sweeteners such as aspartame and stevia may be used in the product as well. These impart sweetness but add no nutritional value and do not depress the freezing point of the product.

Sweetness indices of some sweeteners

Sugar	Relative sweetness
Sucrose	100
HFCS	68
Regular concentrated syrup	50
Fructose	179
Dextrose	74

4. Emulsifiers

These ingredients stabilize the emulsions. The common emulsifiers used in the ice cream mix include:

• Glycerol esters e.g. glycerol monostearate
• Sorbitol esters e.g. polysorbit 65 and 80
• Sugar esters e.g. sucrose monostearate
• Phospholipids e.g. lecithin
• Microcrystalline cellulose
• Dioctyl sodium sulphosuccinate

Functions of emulsifiers

1. Improve the whipping quality of ice cream by producing smaller ice crystals and smaller air cells. This contributes to softer texture of ice cream by making the product stiffer and drier.
2. They stabilize oil in water emulsion of ice cream mix by preventing separation of fat and serum.
3. Reduces the whipping time.
4. Reduces the rate of melting of the finished product.
5. Protects the product from heat shock.

5. Stabilizers

Stabilizers are mostly natural products. They bind the water in the mix and prevent formation of large ice crystals, which also prevent separation of water and the solid phase.

By binding the water, the resultant ice cream has good texture and is resistant to heat shock, both during processing and storage of the finished product.

The amount and type of stabilizer used depends on the composition of the mix, processing conditions (temperatures), and the storage time of the ice cream. Most ice cream mixes have 0.2 – 0.5% added stabilizers.

Some common stabilizers used in ice cream making:

• Sodium arginate, which is derived from marine plants
• Kelp
• Locust bean (has superior heat shock qualities)
• Guar gum
• Gelatin derived from animal sources
• Sodium carboxymethyl cellulose, which has emulsifying properties as well

Functions of Stabilizers

1. They increase the water holding capacity of the product. They are dehydrated before the start of processing but their action starts during processing and continues to storage.
2. Stabilizers impart heat shock resistance to the finished product
3. They give the product good texture and mouth feel
4. Stabilizers also enhance uniform air distribution within the product and increase the viscosity of the product

6. Flavoring and coloring agents

These compounds improve the organoleptic quality of the ice cream. They are added during the mixing stage of the ice cream manufacturing process. If nuts and fruits are to be used, they should be added just before the freezing starts.

Some common flavors and colors used in ice creams include: Vanilla, strawberry, chocolate, annatto, erythrocyn, nuts and fruits.

They increase the consumer appeal and acceptability of the product.

Once all these ingredients have been procured, one can now begin the process of ice cream making. Generally, the following steps apply in the manufacturing process of ice cream.

1. Identification of the ingredients to be used
2. Mix formulation – calculate the proportion of each ingredient to be used in the formula
3. Weighing, measuring, and mixing the ingredients
4. Pasteurization of the mix
5. Homogenization and cooling of the mix
6. Freezing and hardening
7. Extrusion, moulding, and packaging of the ice cream

7. The ice cream overrun

The ice cream overrun is the excess volume of the ice cream you obtain after processing the ice cream mix. This excess volume (expressed as a percentage) consists of air that you incorporate into the mix while freezing.

Control the amount of air to ensure you produce a high-quality product. as a rule, the amount of incorporated air should not exceed 2 -3 times the quantity of total solids in the mix. Too much or too little air will lead to a defective ice cream.

The volume of the ice cream overrun depends on the following factors:

1. Legislative frameworks regulating the market
2. Total solids content in the ice cream mix.
3. Type of ice cream you want to make (whether to incorporate fruits/nuts) and the target selling price
4. Associated production costs

No matter what the determinant is, ensure some level of ethical practice. It would be unethical to incorporate too much air into the product as it would translate to selling air to the customers.

Once you have determined the amount of the ice cream overrun you would want to incorporate in the ice cream, it is time to freeze the mix.

The amount of ice cream overrun you will obtain depends on: 

1. The type of the ingredients you incorporate in the mix.
2.  How sharp the baffle blades are.
3.  The speed of rotation of the dasher.
4.  Temperature and volume of refrigerant passing over the freezing chamber

There are some instances when you may fail to obtain the amount of ice cream overrun you had projected.

Failure to obtain the volume of ice cream overrun may be due to:

1. When the ice cream is too soft. It is heavy hence impedes air incorporation
2. The ice cream forms large ice crystals
3. You draw the mix at higher temperatures than recommended
4. When you take too long to make/obtain the overrun

Whatever the case, ensure that you accurately test for the percentage overrun. Testing the volume of the overrun will help you control the amount of incorporated air.

This is important to ensure that you produce ice cream with consistent quality parameters.

How to calculate the percentage ice cream overrun

As we have already observed, it is important to continuously calculate the volume of the ice cream overrun to control the quality parameters of the ice cream.

You can calculate the percentage ice cream overrun based on either the volume or the weight of the ice cream.

Based on the weight of the ice cream:

Example

If 1000 ml of ice cream mix weighs 1100 gm, and 1000ml of frozen ice cream weighs 550 gm. What will be the percentage ice cream overrun in ice cream?

Solution:

% overrun = {(Wt. unit vol. mix –Wt. unit vol. ice cream)/( Wt. same unit vol ice cream)}*100

% overrun = {(1100-550)/550)*100 = (550/550)*100 =100%

Based on the volume of the ice cream:

Example

If you freeze 20 liters of the ice cream mix to make 38 liters of ice cream, what percentage overrun in the ice cream will you have?

Solution:

% overrun = {[(Vol. ice cream)-( Vol. mix)]/( Vol. mix)}*100

% overrun = {(38-20)/(20)}*100 = 90%